Question

A bag contains 6 red balls some blue balls .if the prbablity of drawing a blue ball is twice the probability of drawing red balls find number of blue balls

Answer 1

Given Red balls = 6 

Let Blue balls  = B

Total balls = B + 6

P(E)of blue balls is double than red balls

then

P(E) blue = 2 x P(E) red

B / B + 6 = 2 x  6 / B + 6

B = 12

Therefore ther are 12 blue balls

Answer 2

See this is a very easy one...

Red ball = 6nos. = p(e) = 6/x
Blue ball = 2 (p(red)) = 12 nos.= 12/x

So sum = x = 12 + 6
x = 18

No of blue ball =12